Polyvinylamine hydrochloride-based microcapsules: polymer synthesis, permeability and mechanical properties

Mechanically stable microcapsules, with sizes of 0.4-1.5 mm, have been produced with permeabilities appropriate for applications involving living cells and controlled delivery. Polyvinylamine hydrochloride was employed alone, in mixtures with poly(methylene-co-guanidine) hydrochloride, or as a coating material for pre-formed capsules, The influence of polymer molar mass, the ratio between the two polycations, the coating time, and the capsule size on the properties of the capsules were analysed. The competitive displacement of one polycation with another in the polysaccharide matrix was also documented. The properties of the capsules vary remarkably, depending of the polyelectrolyte combinations used for their preparation. Specifically, capsules could withstand compressive loads of between 0.09-1.67 N, while the permeability varied from 10-120 kDa. Both are within the ranges required for clinical immunosuppressive therapies.